Beginner’s Guide To PA Systems, Part 4: Cables & Soundchecking

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beginner cables pa systems soundchecking
Last updated 27 March, 2018

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Soundcheck
A soundcheck before a public event in 1929: Now as then, this is an important part of preparing for any live event.

In this fourth and final part of our beginner’s guide to PA systems we cover setting up and soundchecking. You’ll learn about the different types of cables, and how to get all the levels right so everything sounds perfect on the night. Don’t forget to go back if you’ve missed any of the others parts. Part 1 covers the basics, Part 2 answers some common questions, and Part 3 looks more closely at speakers and amplifiers.

Cables

The most important thing is to get good cables. If you try to save money on cables it will always hit you back. PA cables need to withstand abuse, as possibly people will stand on them or walk over them, which can not always be prevented. They will be pushed around at set-up, connected and disconnected hundreds of times and so on. So doing this causes much more stress than setting up your home stereo, where you possibly never again move any cables after the first installation.

Now the most-asked question is how to connect your controller to the PA mixer or power amplifier. First you should identify which cable will connect to your controller. You controller will have sockets that fit one or more of the following cable types: RCA, TRS and XLR.

RCA, TRS or XLR?

The cabling from your controller/DJ mixer to the PA/PA mixer is the most confusing, because it can be RCA, TRS or XLR. The main difference is that RCA is an “unbalanced” connector and cable, and that the TRS and XLR variants are balanced. Now a balanced cable will in general be less prone to interference and can carry even low signals over a larger cable length. However many entry controllers only have RCA outputs.

RCA to TRS
It’s not a perfect solution as it’s unbalanced to balanced, by having RCA to TRS adaptors can get you out of jail – always carry a pair.

This is fine as long as your cable length is shorter than five metres (I recommend two metres). In a venue this can be quite short, but that is OK if you have a PA mixer too. However many PA mixers and power amplifiers (if you decide against the PA mixer) cannot take RCA inputs. So you should at least have a pair of RCA to TRS adapters like those pictured here. If your controller has TRS or XLR outputs, you will be fine on cable lengths up to 8 to 10 meters and any PA mixer and most amplifiers will accept both types as input.

Now I agree that sound may be marginally better if you use balanced cables and connectors (TRS or XLR), as simply we are today in environments where a lot of interference can happen and we generally do not like to have that smartphone disturbing our DJ performances… But also, some people will tell you that XLR is even better than TRS. Sound quality wise I tend to disagree as I found no real world difference in both. One thing hold true however, that is that XLR connectors will lock in place. This can be good or bad. Basically a TRS connector can be yanked out by accident, but then if you have a light controller with XLRs the same accident might yank your controller from the table or even damage the connector.

So there is no definitive answer to this second question. I know people swearing by either type of connector and I tend to simply not overthink it and just use whatever is there.

The rest of the cabling

Now the good thing is, that was the hard part. The rest of the cabling, aka PA mixer to power amplifier and power amplifier to speakers is almost idiot-proof. In 99% of cases the guy who sells you your PA will include the right cables for this, and it is simply XLR cables all around. So XLR from mixer to amp and then from amp to speakers.

XLR cables
Nearly all the rest of the time, all the other cables in your PA system will be XLR.

Some higher-end systems however will have “Speakon” adapters from amp to speakers. Some say to use those over XLR. I have yet to find a real advantage in the set-ups we use and I tend to use XLR all around if I can, simply because it means I do not have to carry many different replacement cables. The Speakons do lock in place even a little better than XLR and I know why they are highly valued in big venues, but for our setups XLR or even TRS are just fine.

I recommend you try the whole cabling thing at home at least three times from scratch, then soundcheck, strip it down and do it again, so you feel comfortable with the set-up of your gear.

Soundchecking

Now that we have powered everything up we need to soundcheck the whole thing.

Powering up & down

Before you power up make sure that all volume knobs and faders are closed/down! Some PA guys make it a science in how to power up and shutdown your gear. However this can all be simplified by following this simple rule: When powering up, go from the source to the output.

So in our basic set-up, fire up your controller and your notebook, then your PA mixer (if present), then the amplifier (or active speakers) and you are good to go. So in our block diagram at the beginning of this series, you’ll go from left to right when powering up. Therefore it stands to reason that when powering down, you should go from output to source: Power down your active speakers/amp first, then PA mixer, then the controller and you are done. So again in our block diagram at the beginning of the series, you’d go from right to left. Yes, it is really that simple.

Performing the soundcheck

As a DJ this is actually quite simple: Put on a long tune or some kind of megamix in your DJ software and start playback. Put the channel fader of the deck you play on to maximum. If you have no PA mixer, then slowly increase the master output of your DJ controller and you should start hearing something from the speakers. Put the volume up to a decent level.

Small PA mixer
If you’re using a PA mixer as well as your controller or DJ mixer, this is your chance to use it to compensate for any vagarities of the room.

If you have a PA mixer, then put your DJ controller master output to 50% and move to your PA mixer. Set the input gain of the PA mixer channel your controller is on, so that the channel is not clipping (there should be an LED that displays if you go over the top). If you have channel VU-meters you should make sure you stay well out of the red part. Then slide the channel fader of your PA mixer to the full up/maximum position (make sure the master output is still closed!). Now slide up (or turn up) the master output volume of the PA mixer and you should start to hear your sound. Turn it up to good listening values.

Now, if you have a PA mixer you can try to play with the EQ a bit to make the sound more natural and good sounding. For this purpose you should listen to the sound from the middle of the venue, then go back to your mixer and adjust. (If you do not have a PA mixer of course you do not have that luxury of tuning possibilities.) If you have more than one sound source (aka microphones, CD players…) do the same thing you just did on your PA mixer. Start with the input gain setting, then move to the channel fader and bring it up so it is OK with the sound of your controller, then do EQing. Now when you go live and people show up, try not to touch the EQ of your PA mixer unless you really have to; if possible only control the volume level (you will most likely need to adjust it a bit when more people arrive) on the master output of your PA mixer.

Congratulations you have the basics of PA systems down. Now go shopping! Just remember: Get good cables, get a small PA mixer if you can, keep it as simple as you can (powered speakers are fine, for instance), and buying cheap often means buying twice. Happy shopping!

Check out the other parts in this series:

Any advice you’d like to add about cabling and soundchecking? Any questions about this final article in the series? Please let us know your thoughts in the comments.

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